gems, history of gemology, turquoise, lapis lazuli, carnelian, jasper, jade

Precious stones: These are those which are made valuable not only due to their rarity and beauty but also because nature has adorned them with a special light and radiance, making them, in a sense, noble—so that they sparkle like the finest stars and have always maintained a higher status than gold or silver. There are two types of precious stones: transparent and opaque. The transparent ones include amethyst, beryl, carbuncle, chrysolite, diamond, hyacinth, ruby, sapphire, and emerald. Among the opaque ones, though some are semi-transparent, are agate, carnelian, chalcedony, jasper, the so-called cat’s eye, lapis lazuli, nephrite, and gallstone, malachite and schreckstein, onyx, opal, turquoise, etc. These precious stones, especially the transparent ones, originate from water or moisture impregnated with mountain salt, which allows them to grow and develop into crystals. It is impossible for something to be transparent that has not first been in liquid form. Dense substances such as silver and lead, when dissolved in separating water or other acidic liquids, can easily grow into transparent crystals. Similarly, one often finds completely clear water droplets inside the most beautifully grown crystals, and in the hardest stones in India, the finest gemstones. Moreover, that there is some mountain salt mixed in is evident from the geometric shape of the precious stones, which are clearly recognizable as having the same structure as salt and saltpeter, as the mined crystals and diamonds, which differ only in hardness, grow entirely angular, often even with veins and such deposits, so that one can clearly see how the salty components have been layered on top of each other. Their charming colors come from a delicate metallic sulfur, similar to metals found in mines: for example, carbuncle, ruby, garnet, and amethyst from a gold-sulfur; sapphire from the tincture of silver; emerald and chrysolite from the greenish-sulfuric nature of copper; topaz and hyacinth from the sulfurous substance of iron, etc. However, this sulfur in precious stones is very volatile, so much so that the colors resulting from it can easily disappear and evaporate in the fire. But since these gemstones, when broken, are often irregular, or unclean and blotchy, even the most beautiful and purest stones do not shine as brightly as when they are cut, whereby the multiple facets reflect and play the light that falls on the foil or diamond ink all the more toward the eye. Therefore, those skilled in this art are called gem cutters, and they practice a free craft; however, they have been regulated by a noble order in Nuremberg for more than 100 years.